Acute Sore Throat

Context

Sore throat accounted for 1.9% of all visits to emergency departments in the USA in 2006 (1). This figure represents a small percentage of the total disease prevalence as only about 15% of people with an upper respiratory tract infection seek medical care (2).

Most sore throats have an unknown or viral aetiology but group A haemolytic streptococcus (GABHS) is identified as the infecting agent in approximately 5 – 15% of all cases (3). GABHS infection may be complicated by significant sequelae such as rheumatic fever, peritonsillar abscess (quinsy) and post-streptococcal glomerulonephritis.

Even though the vast majority of patients with a sore throat have a benign, self-limiting course, one study found that 64% of primary care patients in the UK are prescribed antibiotics for a sore throat (4).

A recent Cochrane review showed that antibiotics give only modest symptomatic relief and only significantly reduce the risk of serious complications in areas where such complications e.g. rheumatic fever are common. (Spinks A, Glasziou PP, Del Mar CB. Antibiotics for sore throat. Cochrane Database Syst Rev 2013.updated)

Learning Bite

Although the minority of sore throats are caused by bacterial infection, almost 2/3 of patients are managed with a course of antibiotics.

Definition

Patients presenting with a sore throat are commonly diagnosed as having either pharyngitis or tonsillitis. However, it is more accurate to consider these diagnoses as part of a spectrum of a single disease process, tonsillopharyngitis, which encompasses infection or inflammation of the pharynx and/or tonsils.

Rarer, more serious problems such as peritonsillar abscess, epiglottitis and retropharyngeal abscess may also present with the symptom of a sore throat, and must be carefully differentiated from tonsillopharyngitis.

Learning Bite

Patients diagnosed with either tonsillitis or pharyngitis should be considered to have an illness which lies within the spectrum of tonsillopharyngitis.

 

Group A β haemolytic streptococcus (streptococcus pyogenes) is the infective agent responsible for the most serious complications of tonsillopharyngitis (image, above, reproduced with permissions from CDC).

 

The M protein GABHS is associated with diseases outside the pharynx, and it is the similarity of some of the serotypes to myocardial sarcolemma antigens that is responsible for the development of rheumatic fever in some patients.

 

A different process of antigen/antibody complex deposition in glomeruli is responsible for the development of post-streptococcal glomerulonephritis.

 

Exotoxins

 

GABHS may also release a variety of exotoxins which are responsible for illnesses such as toxic shock syndrome and necrotising fasciitis. One of these exotoxins, streptolysin O, provokes a reliable immune response which can be measured via the antistreptolysin O titre (ASOT), a standard marker of GABHS infection.

 

Carriage rates

 

GABHS may be carried asymptomatically, maximally between the ages of 3 and 15, where carriage rates have been found between 5% and 21%. In adults, the rates are far lower, lying between 2.4% and 3.7% [5].

 

Complications

 

Untreated GABHS infection normally lasts between 8-10 days with patients remaining infectious during, and one week after, the illness. Complications of GABHS infection are categorised into suppurative and non-suppurative.

 

Suppurative complications

 

Suppurative complications such as otitis media, sinusitis and peritonsillar abscess arise from direct spread of infection into adjacent structures.

 

Non-suppurative complications

 

Non-suppurative complications are far rarer with the most common, rheumatic fever, having an annual incidence of less than 10 cases per 100,000 in western Europe and the USA [6].

 

However, 95% of new cases worldwide occur in the developing world (6) where rheumatic fever remains a significant problem and is responsible for approximately 500,000 deaths annually [7].

 

Learning bite

 

Although rheumatic fever is a rare complication of GABHS infection in the western world, it remains a significant problem in the developing world.

History

In taking a history from a patient with a sore throat, the clinician must enquire about the course and duration of illness as well as other associated symptoms such as fever, headache and vomiting. In severe cases, the ability to swallow may be lost and lead to symptoms and signs of dehydration.

Severe pain, neck stiffness or inability to swallow should also prompt the clinician to consider other, more serious, diagnoses such as epiglottitis and retropharyngeal abscess.

Abdominal symptoms such as pain and vomiting are common in children but the presence of gastrointestinal symptoms does not predict the presence of a streptococcal illness [8].

It is important to identify any history suggestive of immunosuppression or compromise e.g. diabetes, HIV or immunosuppressive medications. Patients on disease-modifying anti-rheumatic drug (DMARDs), carbimazole and chemotherapy may develop neutropaenia or agranulocytosis that present with a sore throat. These patients require an urgent Full Blood Count.

The patient must also be asked about previous non-suppurative complications of GABHS infection, as there is an increased risk of both rheumatic fever and post-streptococcal glomerulonephritis with further GABHS infection.

General Examination

An initial ABC assessment may indicate signs of airway obstruction, respiratory difficulty and circulatory collapse. These findings should prompt the junior clinician to seek experienced help immediately.

Signs of upper airway obstruction:

• Snoring
• Gurgling and/or pooling of saliva
• Stridor
• Hoarse voice
• In complete obstruction paradoxical chest movements

It is important to conduct a general examination of the patient as it may reveal;

• Systemic features of infection such as fever and tachycardia
• Heart murmurs found in rheumatic fever
• Neck stiffness which may indicate lymphadenopathy or rarely, retropharyngeal abscess
• Hepatosplenomegaly found in infectious mononucleosis
• Rash which may be viral in origin but also consider;

Rheumatic fever erythema marginatum

Scarlet fever a rough textured macular rash with confluence in the skin folds (Pastias lines) and red cheeks with perioral sparing.

Examination of the face and neck may identify suppurative complications of GABHS infection e.g. otitis media, mastoiditis, sinusitis. Lymphadenopathy in the neck is common in both viral and GABHS infection but the presence of conjunctivitis is more specifically associated with adenoviral infection.

Examination of the mouth and pharynx should be undertaken with care, in particular do not use a tongue depressor if there are any signs of potential airway obstruction as you may worsen the situation.

Learning Bite

Take care when examining the throat as over-vigorous examination or unnecessary painful procedures may worsen or precipitate airway obstruction.

Specific findings may include:

Finding	Diagnosis
Tonsillopharyngeal or palatal petechiae	GABHS infection or infectious mononucleosis
Unilateral peritonsillar swelling	Peritonsillar abscess
Grey pseudomembrane on the pharynx	Diphtheria
Strawberry tongue	Scarlet fever or Kawasakis disease
Posterior pharyngeal swelling or oedema	Retropharyngeal abscess

Palatal petechiae in GABHS infection

There are a number of red flag symptoms and signs that should prompt the clinician to consider a more serious cause for a sore throat, including:

• Significant systemic upset
• Severe pain
• Stridor
• Severe neck stiffness
• Inability to swallow / drooling of saliva
• Patient holding a tripod position

A patient with signs of potential or partial airway obstruction such as stridor, inability to swallow and holding a tripod position must be assessed urgently by a senior anaesthetist and otolaryngologist. In this situation the patient must not be moved unnecessarily or have any painful procedures undertaken, such as cannulation or blood gas sampling, until specialist support arrives.

Learning Bite

Patients with impending airway obstruction may present with a sore throat. A patient with stridor, inability to swallow or adopting a tripod position must be managed carefully and with senior anaesthetic and otolaryngology support.

Group A Streptococcal infection is more likely in the winter/spring, and in children aged 5-15.

To differentiate between viral causes, and the potentially more serious GABHS infection, a number of tools have been developed to assess the probability of GABHS infection and therefore the need for antibiotic treatment.

The two recommended by NICE [15] are FeverPAIN and CENTOR.

FeverPAIN Score 0-5 (Each scores 1 point)
⦁ Fever over 38°C.
⦁ Purulence (pharyngeal/tonsillar exudate)
⦁ Attend rapidly (3 days or less)
⦁ Severely Inflamed tonsils
⦁ No cough or coryza

CENTOR Score 0-4 (Each scores 1 point)
⦁ Tonsillar exudate
⦁ Tender anterior cervical lymphadenopathy or lymphadenitis
⦁ History of fever (over 38°C)
⦁ Absence of cough

A modified version of CENTOR adds in age to increase accuracy, but is not currently included in NICE guidance [10].

Scores and subsequent likelihood of isolating Streptococcus [15].

FeverPAIN		CENTOR
0 – 1	13 – 18%	0	3%
2 – 3	34 – 40%	1	7%
4 – 5	62 – 65%	2	15%
		3	32%
		4	56%

Learning bite

A sore throat score is useful in predicting the likelihood of GABHS infection and can reduce unnecessary antibiotic prescriptions by 50%.

Note that these scores are not applicable to other causes of sore throat other than tonsillopharyngitis.

There are a number of strategies that can be employed in the investigation of patients with a sore throat:

Rapid streptococcal antigen testing

In the USA, and other countries without universal primary care backup, rapid streptococcal antigen testing has been widely utilised in the ED. The test is claimed to be 95% sensitive and specific but, in some studies, sensitivity has varied between 55% and 90% and has also been found to vary considerably depending on the operator performing the test [12].

In one study carried out in UK ED setting, rapid streptococcal antigen testing was found to have a sensitivity of 66% but 99% specificity [13]. Although included in NICE guidance, not all UK EDs have access to rapid streptococcal antigen testing.

Antistreptolysin O titre (ASOT)

A rising antistreptolysin O titre (ASOT) provides the gold standard criteria for immunologically significant GABHS infection. However, it is impractical and unnecessary in the vast majority of cases of sore throat.

Throat swab

Throat swabs, although widely used, are reliant on correct technique and interpretation is complicated by asymptomatic carriers of GABHS.

Covid-19 swab

It is recognised that sore throat can be a symptom of Covid-19. By itself it is not necessitate a PCR test, however clinicians should consider if there are other symptoms such as fever, new continuous cough or loss/change to sense or taste or smell [24].

Other investigations

Other investigations which may be useful in patients with a sore throat include:

• Routine bloods should be taken if the patient is being cannulated for another reason e.g. unable to swallow. These may show signs of dehydration
• FBC will likely show leucocytosis. A raised WBC count with lymphocytosis and atypical lymphocytes is suggestive of infectious mononucleosis
• Heterophile antibody tests for infectious mononucleosis e.g. Monospot and Paul Bunnell tests
• Deranged liver function tests are present in 90% of patients with Infectious Mononucleosis
• Chest x-ray if respiratory infection is suspected
• Fibreoptic Nasal Endoscopy (FNE) can be performed by ENT specialists in ED to visualise the pharynx and glottis. It is particularly of use in patients presenting with stridor
• Lateral soft tissue neck x-ray for retropharyngeal abscess and epiglottitis.

An epiglottic width (widest anteroposterior diameter of the epiglottis) of >7 mm was found to have a sensitivity and specificity of 100% for the diagnosis of epiglottitis in one study [14] (see image below).

 

Tonsillopharyngitis

The current recommended strategy for the management of uncomplicated tonsillopharyngitis in the UK relies on a pragmatic expectant policy i.e. no initial antibiotics are given and the patient is advised to return to their GP if their symptoms are not settling after a few days [15].

Expectant management

The strategy of expectant management is based on a Cochrane review of antibiotics for sore throat [16]. This found that a course of antibiotics has minimal effect on the course of the illness, shortening it by approximately 16 hours.

Another study found that an antibiotic prescription increases the chance of a patient with a sore throat returning in the future for antibiotics [17]. Despite this evidence, antibiotic prescribing rates remain high. Patient expectation is often quoted as the main reason for this but, in a study conducted in 10 EDs in the USA, patient satisfaction rates were not altered by the decision to prescribe antibiotics for upper respiratory tract infections [18].

Learning bite

Treating an uncomplicated sore throat with antibiotics has little effect on the clinical course of the illness and may encourage patients to return in the future when a similar problem arises. It also increases risk of anti-microbial resistance or side effects.

Antibiotic Prescription

NICE currently advise to consider antibiotic prescription if the FeverPAIN score is 4 or 5, or CENTOR score is 3 or 4, and a rapid streptococcal antigen test is pending or not available. If the FeverPAIN is 2 or 3 then you should consider a delayed antibiotic prescription.

 The threshold is lower if the patient is at risk of rheumatic fever or are vulnerable. Antibiotics should not be withheld if the person has very severe symptoms and there is concern about their clinical condition.

Learning Bite

During Covid-19, RCPCH have recommended only examining children’s’ throats if necessary. If not, they recommend assuming a score 2 in lieu of examination [23].

Antibiotic choice

Phenoxymethylpenicillin QDS for 10 days is the first line choice antibiotic. If the patient is penicillin allergic then recommendation is clarithromycin, or erythromycin if they are also pregnant.

Phenoxymethylpenicillin is normally prescribed as a four times daily regime although, in a meta-analysis, similar cure rates were found for twice daily dosing [19] with consequent better compliance rates.

Amoxicillin and other Ampicillin antibiotics should be avoided in sore throat due to the possibility of causing maculopapular exanthems in patients with infectious mononucleosis.

Other treatment

Simple analgesia including paracetamol, non-steroidal anti-inflammatories and topical local anaesthetic agents (e.g. Benzydramine spray/mouthwash) are effective in patients with a sore throat and may have a greater positive effect than antibiotics alone.

Steroids such as Dexamethasone are frequently used in hospital if the patient is unable to swallow due to severe pain or has stridor.

Other diagnoses

Learning bite

Regardless of the underlying cause, always assess the patient for signs of airway obstruction or dehydration that may require admission.

Common cold

The majority of sore throats are viral in origin. Suggested by rhinorrhoea, coryza, and cough. Can be managed with simple analgesia and rest.

Scarlet fever

Scarlet fever is a GABHS exotoxin-mediated illness which occurs far more commonly in children. Other than standard antibiotic treatment for GABHS, consideration must also be made of hydration status and intravenous fluid rehydration may be required. It is a notifiable disease in England and Wales.

Peri-tonsillar Abscess (Quinsy)

Uncomplicated peritonsillar abscess may be managed in the ED although it is common practice for patients to be referred to an ear, nose and throat (ENT) specialist due to a lack of familiarity with treatment techniques.

Both needle aspiration and incision and drainage techniques may be employed, and have been found to be equally effective [21]. The clinician must be aware of the potential complications of both the problem e.g. Lemierre’s syndrome (extension of infection involving the jugular vein) and its management e.g. accidental puncture of the carotid artery.

Learning bite

Peritonsillar abscess can be treated equally effectively by either needle aspiration or incision and drainage, although the operator must be familiar with both the technique and the potential serious complications.

Patients should receive a broader antibiotic choice than standard pharyngotonsillitis as organisms other than Group A Streptococcus are also likely to be causative (follow local Microbiology guidance).

Infective Mononucleosis

Caused by the Ebstein Barr virus. Suggested by prolonged symptoms, fatigue, generalised lymphadenopathy and hepatosplenomegaly. More common teenagers and young adults. Advise patients that symptoms can take weeks to months to resolve. Patients should avoid kissing and sharing towels or kitchen utensils. They should avoid heavy lifting or contact sports for 1 month due to the risk of splenic rupture. Advise them to return to ED in the event of sudden onset abdominal pain [25].

Learning bite

HIV may present as a sore throat with myalgia, arthralgia, lymphadenopathy and lethargy during seroconversion. Patients being investigated for suspected Infectious Mononucleosis should be considered for HIV testing as well.

Epiglottitis/Supraglottitis

Since the advent of Hib vaccination, epiglottitis is now more commonly an infection affecting adults. The main complication of airway obstruction may be predicted by the presence of specific clinical features [22]:

• Stridor
• Muffled voice
• Rapid clinical course
• History of diabetes

Any patient presenting with these features should be urgently reviewed by anaesthetics and ENT.

A review of 106 patients with epiglottitis found that routine intubation was unnecessary as over 90% of patients recovered with a conservative watchful approach [23].

The main focus of treatment centres on observation for airway obstruction and administration of antibiotics – a third-generation cephalosporin and metronidazole are recommended to cover the spectrum of organisms responsible. Adrenaline nebulisers and Dexamethasone is commonly given to reduce swelling.

Learning bite

Since the advent of Hib immunisation, epiglottitis has become more common in adults and, in the absence of high risk features, can normally be managed with antibiotics and careful observation.

Retropharyngeal Abscess

Although very uncommon, a combination of sore throat, fever, neck stiffness and stridor should alert the clinician to consider this diagnosis. Swelling or oedema of the posterior pharynx should prompt a consideration of advanced airway care and an urgent ENT opinion. Mortality rates are high when complications such as airway obstruction and mediastinitis arise.

• Sore throat is a common presentation to both the ED and primary care and is managed with an over-reliance on antibiotic prescription. (level of evidence 4)
• Non-suppurative complications of GABHS infection are extremely rare in the Western world, although in the developing world, rheumatic fever remains a very significant problem. (level of evidence 5)
• The presence of severe throat pain, stridor, significant systemic upset, neck stiffness, inability to swallow saliva and the patient holding a tripod position are all signs of a more serious cause for a sore throat. (level of evidence 5)
• Clinical features of partial or potential airway obstruction (stridor, altered voice, inability to swallow saliva, tripod position) must be managed by gentle handling of the patient and urgent senior ENT and anaesthetic assessment. (level of evidence 5)
• NICE guidance includes use of both the CENTOR and FeverPAIN scores to assess the likelihood of Group A Streptococcal infection and can reduce unnecessary antibiotic prescription by 50%.
• The treatment of uncomplicated sore throat with antibiotics has little effect on the course of the illness and the use of an expectant or delayed antibiotic policy does not increase the incidence of complications. (level of evidence 1a)
• Simple non-antibiotic treatments such as NSAIDs and paracetamol are effective and may have a larger treatment effect than antibiotics alone. (level of evidence 2a)
• In the absence of features associated with a high risk of airway obstruction, epiglottitis can normally be managed without routine intubation, using a strategy of intravenous antibiotics and close observation. (level of evidence 4)

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